<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			#app{
				width: 100px;
				height: 100px;
			}
		</style>
	</head>
	<body>
		<div id="app">zmq</div>
		<script src="jquery.js" type="text/javascript" charset="utf-8"></script>
		<script type="text/javascript">
			// jq对象获取dom节点。
			console.log(jQuery('#app')[0])
			$('#app').css('background-color','red')
		</script>
	</body>
</html>
